Electric measuring system



Jan. 3, 1928. 1,655,276

G. LICHTSCHEINDL ELECTRIC MEASURING SYSTEM Filed Dec. 30. 1924 2 Sheets-Sheet l Inventor-z Geza Lichtscheindl,

His Attorney Jan. 3,1928.

1,655,276 G. LICHTSCHEINDL ELECTRIC MEASURING SYSTEM Filed Dec. 50. 1924 2 Sheets-Sheet 2 Inventor: Geza Lich'tscheindl,

His Attorney Peas-.1 1.... 3,1928. 1,655,276

UNITED STATES PATENT OFFICE GEZA LICHTSCHEINDL, OF BELGRAD, SERBIA, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC MEASURING SYSTEM. Application filed December 30, 1924, Serial No. 758,966, and in Germany January 30, 1924.

My invention relates to an electric meascircuit arrangement for solving equations uring system or circuit by means of which of the form ic(a bi cb"i v the algebraic relation of variousvariable Referring now to Fig. l 10 represents an quantities represented in the circuit by reordinary source oi potential which may be sistances may be directly indicated. The either direct or alternating and which 18 main object of the invention is to provide a not necessarily absolutely constant. To obmeasuring circuit or system which will intain a constant current from this source, I 60 dicate directly such results as may be indiprovide in this instance, a suitable resistrectly obtained by the use of a Wheatstone ance element represented at 11 which will bridge. Thus, with'the \Vheatstone bridge, allow a substantially contant current to flow it is possible to obtain the products and corthrough it irrespective ot considerable variaresponding quotients of electric resistances. tions in voltage across it. A fine iron wire However, the nature of the Wheatstone having a high temperature coetficient of rebridge is such that a zero indicating instrusistance in a vacuum tube and operated at ment must be used and the actual measureincandescence is suitable for this purpose. ment reading taken from adjustable resist- Connected across the circuit 10 in series with ances. By means of my invention the algethe constant current dev ce 11 is a variable 7 braic relation of variable resistances, which resistance 12 and the active part of this remay represent variable quantities, is directslstance, which may represent some variable 1y indicated on an electrical measuring 1nquantity to be considered, is designated by strument, the deflection of which come the letter a, In shunt to the resistance a is sponds to the answer of the algebraic expresanother resistance 13 WillCh isa very much sion to be solved. higher resistance than 12 and connected In carrying my invention into effect, I across a variable portion 6 of the high resist- 25 provide a circuit made up of a relative low ance 13 IS a voltmeter represented at e. The variable resistance and a relatively high con variable part .2) of the high resistance may be stant resistance connected ,in parallel, prorepresentative of some other variable quanvide means for passing a constant current tity to be considered. The resistance of the through this circuit and connect a measuring voltmeter is also very high as compared to 30 instrument across a variable portion of the the resistance 12 and for all practical purhigh resistance. The variable resistance and poses, the current 2' which flows through the th t o ti f th co tant re i tance resistance a may be considered to be constant across hi h th in t u t i o n t d irrespective of changes in the position of the representvariable factors to be considered voltmeter-tap Without introducing 35 l b i ll T or r h groups ble error in the result to be obtained. The may be combined in various ways as exvoltmeter deflect on e will then be proporpl in d h r inaft t a to ati ally and tional to the resistance volta e drop in the electrically solve involved algebraic expresresistance a times the ratio 0? the resistance Signs, part b to the total resistance 13. Thus,

0 The features of my invention which are 6 believed to be novel and patent-able will be e ia =a X b X]: pointed out in the claims appended hereto. For a better understandin of my invention Where k is a constant.

reference is made in the ollowing descrip- As a practical a 5 tionto the accompanying drawings wherethis measuring circ in Fig. 1 represents a simple embodiment of be made to var my invention for solving simple equations and the resista of the form a b 7c=e. In Fig. 2 the inthe motor; th

vention is arranged for solving equations dicate the 50 of the form (aidic)b7n=e. Fig. 3 reppplication of the use of uit, the resistance a may y as the torque of a motor nee part b as the speed of e instrument 6 then would inpower output of the motor. This principle may be employed in widely dif resents a simplified arrangement of the cirferent modifications and combinations and cuit of Fig. 2 for solving equations of the for the measurement of intricately involved form (a+cl+c) blc=e. Fig. 4 represents a algebraic functions, the variable or variables of which are represented by ohmic resistances.

In Fig. 2 the elements corresponding to 11 and 12 in Fig. 1 are duplicated ,by elements 14: and 15 and the variable part of the resistance 15 is represented by the letter 0. In addition there is connected across the source 10 a graduated resistance element 10 from which maybe obtainedanotherquantity represented by t lie letter (Z' indicative of that part of the resistance 16 between the points where the bonn'ections are made to resistai'ices 12 and 15. Resistance elements 11 and 14: are provided to keep the current in the resistance parts a and 0 constant and these resistances as" well as the part 62 are low as compared to the resistance element 13 shunted across the resistances a, d and 0. Provision is made for reversing the leads to the resistance part d as indicated in dotted lines at 17 so as to add or subtract the factor represented by the resistance d. Provision is also made to connect the lead from resistance element 1 1 to the source 10 to either side as indicated by the dotted line at 18, so as to add or subtract the factor represented by the resistance 0.

Assuming constant voltage of the source 10, the voltage'drop in 01 will be constant for a given setting thereof since the currents flowing through branches a and a are maintained constant by the resistance elements 11 and 14. The voltage impressed on resistance 13 is composed of the algebraic sum of the voltage drop in a, d and a, and the part of that voltage impressed upon the For the connections represented in full lines, the following equation applies:

voltmeter is proportional to If we reverse the leads as indicated in dotted lines at 17 but leave the connection from 14 to the line, as represented in full lines, the equation becomes 6 (a-d-c) 670 Thus we have in Fig. 2 a circuit arrangement for solving equations of the form e= (a d-i0) be.

Where the signs of (Z and c are always positive, the circuit arrangement may be simplified as represented in Fig. 3. Here the parts corresponding to those-of Fig. 2

are similarly designated, (1 representing a constant factor and a, b and 0 factors which may be varied. The equation for Fig. 3 is e=(a+b+d) M32.

Fig. at represents a further modification of the circuit arrangement which is similar to that represented in Fig. 2 except that the high resistance element to which the voltmeter c is connected is divided into two parts 13 and 13'', with variable portions 0 and b which may represent factors to be considered in the algebraic expression. From the explanation previously given, it will be evident that the arrangement of Fig. 1 gives the general equation Two relatively independent voltages cor responding to e in any of the above equatrons may be combined in a single instrument of the wattineter type to obtain the product,

6 e'Xe, or the ratit of T, by means ot a two coil instrument having the coils displ ced by and acting on a common movable indicator provided with a magnetic armature as represented in Fig. 5. The angle of dee flection will then represent the ratio In accordance with the provisions of the patent statutes, 1 have described the principie of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown and described is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric measuring system, a source of potential, a measuring circuit comprising a relatively low variable resistance and a relatively high constant resistance connected parallel, connections from said source to said measuring circuit including means for passing a constant current therethrough, and a measuring instrument connected across a variable portion of said constant resistance.

2. In an electric measuring system, a source of potential, a measuring circuit comprising a relatively low variable resistance and a relatively high constant resistance connected in parallel, connections .from said source to said measuring circuit including an iron wire resistance enclosed in a vacuum and operated at incandescence for maintaining the current flow through the measuring circuit constant, a measuring instrument and means for connecting said instrument across a variable portion of said high constant resistance.

3. A measuring system comprising a plurality of resistances some of which are variable, a source of supply, means for individually supplying constant currents to the variable resistances from said source, means for impressing a voltage across the other of said resistances, and means for measuring a variable portion of the algebraic sum of the voltages across said resistance.

4. An electric measuring system comprising a source of supply, a measuring circuit comprising relatively high and relativel low resistance branches connected in para lel, the low resistance branch including two variable resistances and a constant resistance and the high resistance branch comprising a constant resistance across a variable portion of which is shunted a measuring instrument, circuit connections for impressing a port-ion of the voltage of said source of supply across the constant resistance of the low resistance path, circuit connections for assing current from said source through t e variable resistances, and means for maintaining the current flowing through the variable resistance substantially constant.

5. An electric measuring system according to claim 4, characterized by the fact that means are provided for reversing the direction of the potential impressed upon the constant resistance of the low resistance circuit with respect to the voltages impressed upon the variable resistances.

6. An electric measuring system according to claim 4, characterized by the fact that means are provided for reversing the direction of current flow through one of the variable resistances With respect to the direction of current flow through the other variable resistance.

In Witness whereof, I have hereunto set my hand this 12th day of December, 1924.

GEZA LICHTSCHEINDL. 

